1. Field of the Invention
The present invention relates to an optical semiconductor device housing package for housing an optical semiconductor device, and more particularly to an optical semiconductor device housing package designed to achieve high-efficiency transmission of light emitted by an optical semiconductor device, to an optical fiber.
2. Description of the Related Art
An optical semiconductor device housing package for housing an optical semiconductor device comprises a metal base, a metal frame Joined to the metal base, a fixing member mounted In the metal frame, a light-transmitting member attached to one end portion of the fixing member, and a lid member. The metal base is usually made of an iron-nickel-cobalt alloy, a copper-tungsten alloy, or other metallic material, and a mounting portion for mounting an optical semiconductor device is formed in the center of the upper surface thereof. A plurality of external lead terminals, passing through the metal base from the upper to the lower surface, are rigidly mounted, via an insulating member, around the periphery of the mounting portion. The metal frame is joined to the metal base by a brazing material such as silver brazing, in such a manner as to encircle the mounting portion, and a through-hole is formed in one side of the metal frame. The fixing member is fixed to the through-hole formed in the metal frame, and inside the fixing member is inserted an optical fiber for transferring optical signals from the optical semiconductor device to the outside. The fixing member is made of a metal such as an iron-nickel-cobalt alloy. The light-transmitting member is made of sapphire that closes the inside opening of the cylindrically shaped fixing member. The lid member is bonded to the upper face of the metal frame and hermetically seals the optical semiconductor device.
The optical semiconductor device is rigidly bonded to the mounting portion of the metal base, and the electrodes of the optical semiconductor device are electrically connected to the external lead terminals via bonding wires. Thereafter, the lid member is bonded to the upper face of the metal frame. In this way, the optical semiconductor device is hermetically sealed inside the container including the metal base, metal frame, and lid member, and the optical fiber is inserted in the inside of the cylindrically shaped fixing member.
Then, a driving signal from an external electrical circuit is supplied to the optical semiconductor device via the external lead terminals to drive the optical semiconductor device with the thus supplied driving signal to emit light, and the emission light is transmitted through the sapphire light-transmitting member to the optical fiber to propagation therethrough
The attachment of the light-transmitting member to the cylindrically shaped fixing member is done by first baking a metallized layer of molybdenum-manganese (Mo--Mn) by a known Mo--Mn process at about 1500.degree. C. onto the sapphire forming the light-transmitting member, and then brazing the metallized layer to the cylindrically shaped fixing member with a brazing material composed of a gold-tin alloy or the like.
However, with this prior art optical semiconductor device housing package, when transmitting the light emitted by the optical semiconductor device to the optical fiber via the light-transmitting member, the light emitted by the optical semiconductor device undergoes double refraction in the light-transmitting member in association with the crystallographic axes of the sapphire forming the light-transmitting member, with the result that only a portion of the light is transmitted to the optical fiber. The prior art thus has had the shortcoming that the efficiency of light transmission to the optical fiber, and hence the efficiency of optical signal transmission, degrades.